SPEC: Support existing dirty flag on a (v)FAT file system

[Mike Fedyk]

Onno Benschop wrote:
> As more and more users have access to USB sticks, external drives,
> digital cameras and larger drives that co-exist with other operating
> systems, dosfstools needs to participate in the existing file system
> integrity procedures, rather than just fix every (v)FAT partition it
> encounters.
> 
> https://wiki.ubuntu.com/SpecificationDosDirtyFlag

It is not mentioned, but I assume you intend to support the standard 
flags to check a filesystem even if the dirty flag is not set.  Is that 
right?